American Journal of Epidemiology Advance Access originally published online on September 15, 2008
American Journal of Epidemiology 2008 168(7):673-675; doi:10.1093/aje/kwn162
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Commentary: The Ongoing Legacy—The George W. Comstock Center for Public Health Research and Prevention
From the Prevention and Research Center, Mercy Medical Center, Baltimore, MD
Correspondence to Dr. Kathy J. Helzlsouer, Prevention and Research Center, Mercy Medical Center, 227 St. Paul Place, Baltimore, MD 21202 (e-mail: KHelzlsouer{at}mdmercy.com).
My association with Dr. George W. Comstock began just before the conduct of the second of two community-based cohort studies in Washington County, Maryland. I was in search of a thesis topic for my clinical epidemiology fellowship and was directed to Dr. Comstock—the "go to" person for research ideas. He pulled out his "idea box" and said: "How about looking at micronutrients and bladder cancer in the CLUE study?" Thus began my long-term affiliation with Dr. Comstock and the Training Center for Public Health Research.
The article on the history of the Washington County Training Center for Public Health Research reprinted in this issue of the Journal (1) covers the activities of the Center through 1991, just a few years after the second community-based cohort (CLUE II) was established. Dr. Comstock outlined the rich history of the public health activities conducted in Washington County, culminating in the establishment of the Training Center. As exemplified by its name, the Center was to be a laboratory for public health research, contributing to the education of countless public health researchers and practitioners. Dr. Comstock was the model of the educator and practitioner. Even in the article on the history of the center (1), he inserted multiple "teaching moments," and the article is well worth the read. The only thing missing in the article is the acknowledgment of Dr. Comstock's incredible contributions to the growth and development of the Center, which is now named for him. That, of course, is due to the humility of the author.
The Training Center was officially established in 1962, and Dr. Comstock was there at the beginning. A private census of the county was accomplished in 1963, with nearly complete enumeration of households and completion of a questionnaire on each household member that has provided a rich resource of data for investigations. In addition to the usual questions on age, sex, and the education of each household member, the survey questionnaire also asked about smoking history, religion and frequency of religious service attendance, house characteristics, the presence of animals or pets, the source of drinking water, and whether the house had a telephone. The census, in conjunction with the existing County Cancer Registry, set the stage for the development of cohort studies in the county to study the etiology of cancer.
Dr. Comstock conducted another private census in 1975, with at least a 90 percent enumeration of the county, this time adding in questions on occupation, disability, and history of cancer for household members. The 1975 survey was conducted in the year following the establishment of the first of two CLUE cohorts, allowing accurate assessment of participation rates. These surveys have been used to test numerous hypotheses, such as the association between active smoking and environmental tobacco smoke and outcomes such as cancer, heart disease, and micronutrient concentrations (2–5); cats in the household and toxoplasmosis (6); religious attendance and mortality (7); and source of drinking water and cardiovascular disease and cancer (8, 9). The data also served to teach countless students the basics of case-control and cohort designs in epidemiologic methods courses of the Department of Epidemiology in what is now called the Johns Hopkins Bloomberg School of Public Health, in addition to providing the basis for numerous doctoral dissertations. With the extremely well-characterized smoking history for all members of a household, numerous investigations on the hazards of environmental tobacco smoke have been possible.
Dr. Comstock assumed directorship of the Training Center after a career focused primarily on tuberculosis control in the Public Health Service. He established the CLUE cohort in 1974, turning his attention to chronic disease and making a long-term research investment at an age when most individuals are winding down their careers and thinking of retirement. Needless to say, he never really retired, writing and reviewing papers in the weeks before his death in the summer of his 93rd year. He provided the fertile territory for other multicenter cohort studies to be conducted in Washington County, including the Atherosclerosis Risk in Communities (ARIC) Study and the Cardiovascular Health Study (CHS). He participated in every study conducted in Washington County as he followed the tenet that a researcher should never ask others to do something that he would not do himself. The CLUE studies remain his "home-grown" crowning achievement.
This first cohort was referred to as the "CLUE cohort." Dr. Comstock, never one for acronyms, based the nickname on the recruitment campaign slogan, "Operation CLUE: Campaign against cancer and stroke, give us a clue." The second CLUE cohort, conducted in 1989, built on this same campaign theme and became "Operation CLUE II: Give us a clue: Campaign against cancer and heart disease." The incentive for participating in the first CLUE cohort was a blood pressure reading. For CLUE II, cholesterol concentrations were measured with the results sent to each participant as the incentive for joining, and concerted effort was made to encourage previous participants to give again. Among the CLUE I Washington County resident participants, 8,394 did take part again in CLUE II.
Dr. Comstock had the remarkable foresight to expand the repository collection for CLUE II to include not only plasma but also buffy coat (as a DNA source), red blood cells, and toenails. These cohorts have advanced knowledge of not only cancer etiology and risk prediction but also other chronic diseases, such as heart disease and rheumatoid arthritis. Although numerous diseases other than cancer have been studied, a major focus of the CLUE cohort investigations has been on cancer outcomes, made possible because of the high-quality Washington County Cancer Registry that has been in place since the 1950s. Registries such as these are vital to the conduct of research as well as for public health planning. The tremendous value of the repository collections is now being fully realized, in particular, the value of the DNA repository. The CLUE cohorts have made contributions to the study of candidate genes and risk of cancer and other diseases (10–15) and to studies using whole genome-wide scanning in search of genetic contributions to chronic diseases (16). Because of the accompanying questionnaire data, studies such as the CLUE cohorts provide the resources not only to examine genetic factors but also to explore the influence of both environmental and genetic factors on the development of disease.
In the 1991 article, the CLUE cohorts were described as ranking among the largest in the world with over 50,000 specimens, together with diet histories, and Comstock et al. stated: "The future for public health research in Washington County looks increasingly bright" (1, p. 1028). I wish I could state the same today in 2008. However, in this era of "Big Science," 50,000 is now considered a small sample size. Genetic studies, where relative risks are small, emphasize the p value over clinical significance, so samples' size must be very large. Thus, consortium studies, combining several cohorts, are the wave of the future. These network studies, however, have costs that are rarely acknowledged. There is an inefficiency that comes with large study networks—large steering committees, delays due to the difficulties in achieving consensus across many groups, challenges of combining data collected in disparate ways, and authorship policies and lists that may stretch around the block, if not half-way across the world. There is also the cost to the cohorts in terms of loss of infrastructure support. In an effort to allow maximum money to conduct assays for the largest number of specimens, budgets to the cohorts are not sufficient to cover maintenance costs of specimens (freezer replacement, electricity), data (storage, updating), or ongoing disease registries. There is also the danger of not addressing the concerns and problems of the local community, which may be lost in the sea of national and international interests that do not reflect regional differences. Finally, there is the ultimate potential loss due to "putting all the eggs in one basket." One of Dr. Comstock's caveats was that smaller studies and replication are better than one large study: "Never put all your eggs in one basket."
Hopefully, the tide will turn, and the future will once again look bright for community-based research. The value of local research to address public health problems is priceless but, unfortunately, poorly valued. However, research priorities, such as funding opportunities, are cyclical. The Training Center has contributed and will continue to contribute to the health of the public on the local, regional, national, and international levels.
In 2003, the Training Center for Public Health Research was renamed the George W. Comstock Center for Public Health Research and Prevention in honor of Dr. Comstock and his contributions. The CLUE cohorts remain an outstanding resource and a rich source for future investigations. The Center is indeed an "exemplar of public health research." Dr. Comstock was never happier than when he was knee deep in the community doing research and, as we look toward the future, we should again take stock in the words of Dr. Comstock: "A training center with its roots in a county health department can be a valuable resource base for the demonstration, evaluation, and improvement of local public health services" (1, p. 1028).
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ACKNOWLEDGMENTS |
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Conflict of interest: none declared.
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- Comstock GW, Bush TL, Helzlsouer KJ, et al. The Washington County Training Center: an exemplar of public health research in the field. Am J Epidemiol (1991) 134:1023–9.
[Free Full Text] - Helsing KJ, Sandler DP, Comstock GW, et al. Heart disease mortality in nonsmokers living with smokers. Am J Epidemiol (1988) 127:915–22.
[Abstract/Free Full Text] - Sandler DP, Comstock GW, Helsing KJ, et al. Deaths from all causes in non-smokers who lived with smokers. Am J Public Health (1989) 79:163–7.
[Abstract/Free Full Text] - Alberg AJ, Kouzis A, Genkinger JM, et al. A prospective cohort study of bladder cancer risk in relation to active cigarette smoking and household exposure to secondhand cigarette smoke. Am J Epidemiol (2007) 165:660–6.
[Abstract/Free Full Text] - Alberg AJ, Chen JC, Zhao H, et al. Household exposure to passive cigarette smoking and serum micronutrient concentrations. Am J Clin Nutr (2000) 72:1576–82.
[Abstract/Free Full Text] - Ganley JP, Comstock GW. Association of cats and toxoplasmosis. Am J Epidemiol (1980) 111:238–46.
[Abstract/Free Full Text] - Comstock GW, Partridge KB. Church attendance and health. J Chronic Dis (1972) 22:665–72.
- Comstock GW, Cauthen GM, Helsing KJ, et al. Stroke-associated deaths in Washington County, Maryland, with special reference to water hardness. Stroke (1979) 10:199–205.
[Abstract/Free Full Text] - Wilkins JR 3rd, Comstock GW. Source of drinking water at home and site-specific cancer incidence in Washington County, Maryland. Am J Epidemiol (1981) 114:178–90.
[Abstract/Free Full Text] - Gallicchio L, Chang H, Christo DK, et al. Single nucleotide polymorphisms in inflammation-related genes and mortality in a community-based cohort in Washington County, Maryland. Am J Epidemiol (2008) 167:807–13.
[Abstract/Free Full Text] - Gallicchio L, McSorley MA, Newschaffer CJ, et al. Body mass, polymorphisms in obesity-related genes, and the risk of developing breast cancer among women with benign breast disease. Cancer Detect Prev (2007) 31:95–101.[CrossRef][Web of Science][Medline]
- Huang HY, Thuita L, Strickland P, et al. Frequencies of single nucleotide polymorphisms in genes regulating inflammatory responses in a community-based population. (Electronic article). BMC Genet (2007) 8:7.[CrossRef][Medline]
- Visvanathan K, Crum RM, Strickland PT, et al. Alcohol dehydrogenase genetic polymorphisms, low-to-moderate alcohol consumption, and risk of breast cancer. Alcohol Clin Exp Res (2007) 31:467–76.[CrossRef][Web of Science][Medline]
- Berndt SI, Huang WY, Fallin MD, et al. Genetic variation in base excision repair genes and the prevalence of advanced colorectal adenoma. Cancer Res (2007) 67:1395–404.
[Abstract/Free Full Text] - Genkinger JM, Platz EA, Hoffman SC, et al. C47T polymorphism in manganese superoxide dismutase (MnSOD), antioxidant intake and survival. Mech Ageing Dev (2006) 127:371–7.[CrossRef][Medline]
- National Cancer Institute. US National Institutes of Health. Epidemiology and genetics research. Pancreatic Cancer Cohort Consortium. Bethesda, MD. Epidemiology and Genetics Research Program, Division of Cancer Control and Population Sciences, National Cancer Institute, 2008. (http://epi.grants.cancer.gov/PanScan). (Accessed May 2 2008).
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